Structure and methods of forming the structure

ABSTRACT

Structures, including a capacitor, and methods for forming the structures are provided. One such structure may include a first conductor a second conductor above the first conductor, and a dielectric between the first conductor and the second conductor. The dielectric does not cover a portion of the first conductor; and the second conductor does not cover the portion of the first conductor not covered by the dielectric. Other structures and methods are disclosed.

PRIORITY APPLICATION

This application is a divisional of U.S. application Ser. No.13/214,902, filed Aug. 22, 2011, now issued as U.S. Pat. No. 9,082,555,which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to capacitors and, in aparticular embodiment, to a parallel plate capacitor for storing andproviding electrical energy to a variety of devices, includingsemiconductor devices.

BACKGROUND

Capacitors are a basic electrical element used in storing and providingelectrical energy to other electrical elements. They are used in most oftoday's electrical and/or electronic devices and continue to expand itsrange of applications into new types of hi-tech devices, such assemiconductor devices, as technologies rapidly evolve. While there are avast array of capacitors (e.g., metal oxide field effect transistor(MOSFET) capacitors) available to be used in such semiconductor devices,as the density of the semiconductor devices have exponentially andsteadily increased over the years, there have been incessant andincreasing demands for capacitors that are smaller in size but greaterin storage capacity.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A shows a perspective view of one illustrative embodiment of acapacitor.

FIG. 1B shows a cross-sectional view of the capacitor shown in FIG. 1Ataken along line A-A′.

FIG. 1C shows a planar view of the capacitor shown in FIG. 1A.

FIG. 2A shows a perspective view of another illustrative embodiment of acapacitor.

FIG. 2B shows a cross-sectional view of the capacitor shown in FIG. 2Ataken along line B-B′.

FIG. 2C shows a planar view of the capacitor shown in FIG. 2A.

FIG. 2D shows a schematic circuit diagram of the capacitor shown in FIG.2A.

FIG. 3A shows a perspective view of yet another illustrative embodimentof a capacitor.

FIG. 3B shows a cross-sectional view of the capacitor shown in FIG. 3Ataken along line C-C′.

FIG. 3C shows a cross-sectional view of the capacitor shown in FIG. 3Ataken along line D-D′.

FIG. 3D shows a planar view of the capacitor shown in FIG. 3A.

FIGS. 4A and 4B show a planar view of illustrative embodiments ofcapacitors including four contact electrodes.

FIG. 5 shows a cross-sectional view of an illustrative embodiment of aflash memory device including a capacitor.

FIG. 6 shows an illustrative embodiment of a charge pump includingmultiple capacitors.

FIG. 7 shows an example flow diagram of an illustrative embodiment of amethod for fabricating a capacitor.

FIGS. 8A-8G are a series of diagrams illustrating the example methodshown in FIG. 7 and the structures fabricated by the example method.

FIG. 9 shows a schematic diagram of an illustrative embodiment of asystem including a non-volatile memory device.

DETAILED DESCRIPTION

Techniques relating to a capacitor are provided. In one embodiment, thecapacitor may include a first conductor, a second conductor above thefirst conductor, and a dielectric between the first conductor and thesecond conductor. The dielectric does not cover a portion of the firstconductor; and the second conductor does not cover the portion of thefirst conductor not covered by the dielectric.

In another embodiment, a capacitor may include N planar conductorsdisposed one above the other, each of the planar conductors including atleast one first portion not covered by the planar conductor disposedabove thereof, wherein N is a natural number equal to or greater thantwo.

The foregoing embodiments are illustrative only and are not intended tobe in any way limiting. In addition to the illustrative aspects,embodiments, and features described above, further aspects, embodiments,and features will become apparent by reference to the drawings and thefollowing detailed description.

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented herein. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe Figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated herein.

FIG. 1A shows a perspective view of one illustrative embodiment of acapacitor. FIG. 1B shows a cross-sectional view of the capacitor shownin FIG. 1A taken along line A-A′. FIG. 1C shows a planar view of thecapacitor shown in FIG. 1A. Referring to FIGS. 1A-1C, a capacitor 100may include a substrate 110, and a stacked body 120 provided onsubstrate 110. While not expressly illustrated in FIGS. 1A-1C for thesake of simplicity, a dielectric material, such as silicon oxide, may beinterposed between substrate 110 and stacked body 120. Stacked body 120may include first and second planar conductors (e.g., first and secondplanar conductive layers 121 a and 121 b; hereinafter may becollectively referred to as planar conductive layers 121) disposed oneabove the other and substantially parallel to each other, and adielectric (e.g., a dielectric layer 122) interposed therebetween. Inone embodiment, second planar conductive layer 121 b and dielectriclayer 122 may be disposed on first conductive layer 121 a torespectively cover only a portion(s) of the upper surface of underlyingfirst conductive layer 121 a, such that first conductive layer 121 a mayinclude one or more upper surface portions that are not covered byoverlying second planar conductive layer 121 b and dielectric layer 122(e.g., first and second upper surface portions 12 a and 12 b). By way ofa non-limiting example, one or more upper surface portions 12 a and 12 bmay be the end portions of first planar conductive layer 121 a, suchthat they, together with second planar conductive layer 121 b and firstdielectric layer 122, may form one or more stair steps at one or moresides of capacitor 100.

In one embodiment, as shown in FIGS. 1A-1C, second planar conductivelayer 121 b may be smaller than its underlying first planar conductivelayer 121 a in at least one of its two extending dimensions. Forconvenience of description, an xyz coordinate system is shown in FIG.1A. The x and z axes in the this coordinate system respectively indicatethe two orthogonal directions along which planar conductive layers 121may extend, and the z axis indicate the direction that is orthogonal tothe x and y axes. In the above coordinate system, second planarconductive layer 121 b may be smaller than its underlying first planarconductive layer 121 a in at least one of the two dimensions in thedirections of x and y axes shown in FIG. 1A. Further, in the aboveembodiment, second planar conductive layer 121 b may be equal to orsmaller than its underlying dielectric layer 122 in at least one of itstwo extending dimensions (e.g., the two dimensions in the direction of xand y axes shown in FIG. 1A). However, it should be appreciated that astacked body in accordance with the present disclosure is not limitedthereto, and depending on particular embodiments, the second planarconductive layer may be equal to or greater in size in at least one ofits two extending dimensions than at least some of its underlying firstplanar dielectric layers and/or dielectric layer, and still may bearranged in a manner that cover only a portion(s) of the upper surfaceof the first conductive layer.

In one embodiment, capacitor 100 may further include first and secondcontacts 130 a and 130 b (which, hereinafter, may be collectivelyreferred to by example as metal lines 130) (e.g., metal contacts,poly-silicon contacts, etc.) respectively coupled to the upper surfacesof first and second planar conductive layers 121 a and 121 b, and firstand second contact electrodes 140 a and 140 b (hereinafter may becollectively referred to as contact electrodes 140) respectivelydisposed on and coupled to first and second metal lines 130 a and 130 b.First and second metal lines 130 a and 130 b may be buried inside aninterlayer dielectric layer 150, and first and second contact electrodes140 a and 140 b may be disposed on interlayer dielectric layer 150 to berespectively coupled to first and second metal lines 130 a and 130 b.

By way of a non-limiting example, metal lines 130 may respectivelyextend in the direction substantially perpendicular to the uppersurfaces of planar conductive layers 120 (e.g., in the directionindicated by the z axis shown in FIG. 1A). It should be appreciated thatthe term “substantially perpendicular,” as used herein, includes, but isnot limited to, a range of from −30 to +30 degrees around theperpendicular direction. While metal lines 130 are illustrated as anelongated rectangular structure, they may take one of a variety ofdifferent shapes. For example, metal lines 130 may be, but are notlimited to, a cylinder or a tapered column.

The aforementioned elements of capacitor 100 may respectively be made ofvarious different materials. For example, substrate 110 may befabricated from one or more materials, which include, but are notlimited to, sapphire, glass, or semiconductor materials (e.g., silicon(Si), germanium (Ge), and gallium arsenide (GaAs)). Planar conductivelayers 121 and dielectric layer 122 may be respectively made of aconductive material (e.g., polysilicon) and an oxide of the conductivematerial (e.g., silicon oxide) in any available manner. Metal lines 130and contact electrodes 140 may respectively be made of tungsten andaluminum. Interlayer dielectric layer 150 may be made ofborophosphosilicate glass (BPSG). It should be appreciated, however,that the aforementioned materials are given for illustrative purposesonly, and other materials may be used as appropriate depending on eachimplementation.

In the embodiment described with reference to FIGS. 1A-1C, planarconductive layers 121 and dielectric layer 122 are arranged in a waysuch that first conductive layer 121 a includes one or more portions(e.g., first and second upper surface portions 12 a and 12 b) notcovered by overlying second conductive layer 121 b and dielectric layer122, so as to allow forming of one or more contacts (e.g., first metalline 130 a) and one or more contact electrodes (e.g., first contactelectrode 140 a) from top-down. The aforementioned arrangement not onlyallows its easy fabrication using one or more of existing semiconductorfabrication techniques (e.g., concurrently with other semiconductordevices, such as an array of three-dimensional non-volatile memorycells), but also allows attaining high capacitance, to a level hithertonot possible, by, for example, stacking similarly configured additionalplanar conductive layers and dielectric layers therein.

In this regard, FIGS. 2A-2D show another illustrative embodiment of acapacitor. FIG. 2A shows a perspective view of another illustrativeembodiment of a capacitor. FIG. 2B shows a cross-sectional view of thecapacitor shown in FIG. 2A taken along line B-B′. FIG. 2C shows a planarview of the capacitor shown in FIG. 2A. FIG. 2D shows a schematiccircuit diagram of the capacitor shown in FIG. 2A. Referring to FIGS.2A-2D, a capacitor 200 may include a substrate 210, a stacked body 220,a plurality of contacts 230 a-230 d (which, hereinafter, may becollectively referred to by example as metal lines 230), first andsecond contact electrodes 240 a and 240 b (which hereinafter may becollectively referred to as contact electrodes 240), and an interlayerdielectric layer 250. While not expressly illustrated in FIGS. 2A-2D forthe sake of simplicity, a dielectric material, such as silicon oxide,may be interposed between substrate 210 and stacked body 220. Stackedbody 220 may include N planar conductors (e.g. N planar conductivelayers 221 a-221 d, which hereinafter may be collectively referred to asplanar conductive layers 221) respectively disposed one above the otherand N−1 dielectrics (e.g. N−1 dielectric layers 222 a-222 c, whichhereinafter may be collectively referred to as dielectric layers 222)respectively interposed between two adjacent conductive layers 221.While stacked body 220 of the illustrative embodiment shown in FIGS.2A-2D include four planar conductive layers 221 and three dielectriclayers 222 (i.e., N is equal to 4), a stacked body in accordance withthe present disclosure is not limited thereto, and may include anynumber of planar conductive layers and dielectric layers (e.g., N may beequal to a natural number equal to or greater than 2). It should benoted that numerals in FIGS. 2A-2D that are similar to those in FIGS.1A-1C generally identify similar components, and unless context dictatesotherwise, the descriptions provided with reference to FIGS. 1A-1Cgenerally apply to corresponding components in FIGS. 2A-2D.

Planar conductive layers 221 and dielectric layers 222 may bealternately disposed one above the other to respectively cover only aportion(s) of the upper surfaces of its underlying planar conductivelayers 221, such that each of planar conductive layers 221 may includeat least one portion (e.g. upper surface portions 22 a-22 f) not coveredby its overlying planar conductive layers 221 and dielectric layers 222.By way of a non-limiting example, the at least one upper surface portionmay be an end portion of one of planar conductive layers 221, such thatthe upper surface portions collectively form one or more stair steps atone or more sides of stacked body 220 of capacitor 200 (e.g., the twosteps respectively at the right and left sides of stacked body 220viewed in the direction of the y axis shown in FIG. 2A).

In one embodiment, as shown in FIGS. 2A-2C, each of planar conductivelayers 221 may be smaller than all of its underlying planar conductivelayers 221 in at least one of its two extending dimensions (e.g., thetwo dimensions in the direction of x and y axes shown in FIG. 2A).Further, in the above embodiment, each of planar conductive layers 221may be equal to or smaller than all of its underlying planar dielectriclayers 222 in at least one of its two extending dimensions (e.g., thetwo dimensions in the direction of x and y axes shown in FIG. 2A).However, it should be appreciated that a stacked body in accordance withthe present disclosure is not limited thereto, and depending onparticular embodiments, may include one or more planar conductive layersthat are equal to or greater in size than all or some of its underlyingplanar dielectric layers and/or dielectric layers in at least one of itstwo extending dimensions.

One set of the plurality of contacts 230 (e.g., metal lines 230 a and230 c) may be disposed at one side of stacked body 220 of capacitor 200(e.g., the left side of stacked body 220 viewed in the direction of they axis shown in FIG. 2A) and may be respectively coupled to the uppersurface portions of alternate ones of planar conductive layers 221(e.g., odd-numbered planar conductive layers 221) that are not coveredby respective overlying planar conductive layers 221 and dielectriclayers 222 (e.g., upper surface portions 22 a and 22 e of planarconductive layers 221 a and 221 c). Further, another set of theplurality of contacts 230 (e.g., metal lines 230 b and 230 d) may bedisposed at another side of stacked body 220 of capacitor 200 (e.g., theright side of stacked body 220 viewed in the direction of the y axisshown in FIG. 2A) and may be respectively coupled to one of the uppersurface portions of the remaining ones of the planar conductive layers(e.g., even-numbered planar conductive layers 221), some of which arenot covered by respective overlying planar conductive layers 221 anddielectric layers 222 (e.g., upper surface portions 22 d of planarconductive layers 221 b). First contact electrode 240 a may be disposedon and coupled to the one set of the plurality of contacts lines 230,whereas second contact electrode 240 b may be disposed on and coupled tothe another set of the plurality of contacts 230. Contacts 230 may beburied inside interlayer dielectric layer 250, and contact electrodes240 may be disposed on interlayer dielectric layer 250 to be coupled tocontacts 230.

As can be seen from FIG. 2D, the aforementioned arrangement of stackedbody 220 is the equivalent of N−1 capacitors connected in parallelbetween two nodes A and B respectively corresponding to contactelectrodes 240 a and 240 b. In the example shown in FIG. 2D, C1, C2, andC3 respectively represent capacitances provided between planarconductive layers 221 a and 221 b, planar conductive layers 221 b and221 c, and planar conductive layers 221 c and 221 d. Between each pairof conductive layers, one capacitance is provided at the center portionsof the planar conductive layer pair and another capacitance is providedat the end portions of the planar conductive layer pair. In someembodiments, the total capacitance provided by stacked body 220 may beexpressed by Equation 1 shown below.

$\begin{matrix}\begin{matrix}{C_{total} = {C_{center} + C_{side}}} \\{= {\beta*\left( {{W*L*P_{n}} + {W*\alpha*\left( {S - 2} \right)*\left( {S - 1} \right)}} \right)}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$where, C_(total) is the total capacitance provided by stacked body 220,C_(center) is the capacitance provided between the center portions ofplanar conductive layers 221 in stacked body 220, C_(side) is thecapacitance provided between the end portions of planar conductivelayers 221 in stacked body 220, is the unit capacitance between a planarconductive layer pair, W is the length of planar conductive layers 221along the y axis shown in FIG. 2A, L is the length of planar conductivelayer 221 d along the x axis shown in FIG. 2A, P_(n) is the number ofdielectric layers 222 (i.e., N−1), S is the number of planar conductivelayers 221 (i.e., N), and a is the length of an upper surface portion 22a-22 d along the x axis shown in FIG. 2A. As can be appreciated fromFIG. 2D and Equation 1 shown above, the total capacitance provided bycapacitor 200 is proportional to and thus may be increased by stackingsimilarly configured additional planar conductive layers and dielectriclayers in its stacked body 220.

In the illustrative embodiment shown in FIGS. 2A-2D, contact electrodes240 a and 240 b are disposed above two stair steps located at twoopposing ends of capacitor 200. This is the same for the illustrativeembodiment shown in FIGS. 1A-1C. It should be appreciated, however, thatcontact electrodes in accordance with the present disclosure (andcontacts to be coupled thereto) may be disposed in a variety ofdifferent ways.

In this regard, FIGS. 3A-3D show another illustrative embodiment of acapacitor. FIG. 3A shows a perspective view of yet another illustrativeembodiment of a capacitor. FIG. 3B shows a cross-sectional view of thecapacitor shown in FIG. 3A taken along line C-C′. FIG. 3C shows across-sectional view of the capacitor shown in FIG. 3A taken along lineD-D′. FIG. 3D shows a planar view of the capacitor shown in FIG. 3A.Referring to FIGS. 3A-3D, a capacitor 300 may include a substrate 310, astacked body 320, a plurality of contacts 330 a-330 d (which,hereinafter, may be collectively referred to by example as metal lines330), first and second contact electrodes 340 a and 340 d (whichhereinafter may be collectively referred to as contact electrodes 340),and an interlayer dielectric layer 350. Stacked body 320 may include Nplanar conductors (e.g. N planar conductive layers 321 a-321 d, whichhereinafter may be collectively referred to as planar conductive layers321, where N is a natural number greater than or equal to 2)respectively disposed one above the other and N−1 dielectrics (e.g. N−1dielectric layers 322 a-322 c, which hereinafter may be collectivelyreferred to as dielectric layers 322) respectively interposed betweentwo adjacent conductive layers 321 a-321 d. While not expresslyillustrated in FIGS. 3A-3D for the sake of simplicity, a dielectricmaterial, such as silicon oxide, may be interposed between substrate 310and stacked body 320. Numerals in FIGS. 3A-3D similar to those in FIGS.1A-1C and 2A-2D generally identify similar components, and unlesscontext dictates otherwise, the descriptions provided with reference toFIGS. 1A-1C and 2A-2D generally apply to corresponding components inFIGS. 3A-3D. For the sake of simplicity, some of the features ofcapacitor 300 that are similar to those of capacitors 100 and 200 maynot be described in the ensuing descriptions.

In one embodiment, planar conductive layers 321 and dielectric layers322 may be alternately disposed one above the other to respectivelycover end portions at one side of each upper surface of its underlyingplanar conductive layers 321, such that each of planar conductive layers321 may include an end portion at the opposing side of its upper surface(e.g. upper surface portions 32 a-32 c) that is not covered by itsoverlying planar conductive layers 221 and dielectric layers 322, whilethe end portion on the one side of its upper surface is completelycovered by its overlying planar conductive layers 321 and dielectriclayers 322. In the above embodiment, planar conductive layers 321 anddielectric layers 322 collectively form only one stair step at the oneside of stacked body 320 of capacitor 300 (e.g., the step at the leftside of capacitor 300 viewed in the direction of the y axis shown inFIG. 3A), as opposed to two stair steps along the both sides of each ofstacked bodies 120 and 220 in capacitors 100 and 200 of FIGS. 1A-1C and2A-2D.

In the above embodiment, one set of the plurality of contacts 330 (e.g.,metal lines 330 a and 330 c) may be disposed adjacent to one lateralside of the step formed by stacked body 320 (e.g., the direction alongthe x axis shown in FIG. 3A) and coupled to the upper surface portionsof a first set of conductors, such as odd-numbered planar conductivelayers 321 (e.g., upper surface portions 32 a and 32 c of planarconductive layers 321 a and 321 c). Further, another set of theplurality of contacts 330 (e.g., metal lines 330 b and 330 d) may bedisposed adjacent to the other lateral side of the step formed bystacked body 320 (e.g., the direction along the x axis shown in FIG. 3A)and coupled to the upper surface portions of a second set of conductors,such as even-numbered planar conductive layers 321, some of which arenot covered by its overlying planar conductive layers 321 and dielectriclayers 322 (e.g., upper surface portions 32 d of planar conductivelayers 321 b).

Further, first and second contact electrodes 340 a and 340 b may both bedisposed along a direction substantially parallel to the lateral sidesof the step formed on stacked body 320 (e.g., the direction along the xaxis shown in FIG. 3A) and be spaced apart from each other by aprescribed distance in a direction perpendicular to the lateral sides ofthe step formed on stacked body 320 (e.g., the direction along the yaxis shown in FIG. 3A), such that first contact electrode 340 a may becoupled to a set of contacts coupled to the upper surface portions ofodd-numbered planar conductive layers 321, while second contactelectrode 340 b may be coupled to another set of contacts coupled to theupper surface portions of even-numbered planar conductive layers 321.Contacts 330 may be buried inside interlayer dielectric layer 350, andcontact electrodes 340 may be disposed on interlayer dielectric layer350 to be coupled to contacts 330.

In the illustrative embodiment shown in FIGS. 1A-1C, 2A-2D and 3A-3D,capacitors 100-300 each include two contact electrodes. It should beappreciated, however, that capacitors in accordance with the presentdisclosure may include three or more contact electrodes.

In this regard, FIGS. 4A and 4B show a planar view of illustrativeembodiments of capacitors including four contact electrodes. Referringto FIGS. 4A and 4B, each of capacitors 401 and 402 include four contactelectrodes (i.e., contact electrodes 441 a-441 d and 442 a-442 d) thatare disposed in a direction perpendicular to the lateral sides of thesteps formed in capacitors 401 and 402 (e.g., the direction along the xaxis shown in FIGS. 4A and 4B). Two contact electrodes that are disposedon contacts coupled to a first set of planar conductors, such asodd-numbered planar conductive layers (e.g., contact electrodes 441 aand 441 c coupled to contacts 431 a in FIG. 4A, and contact electrodes442 a and 442 c coupled to contacts 432 a in FIG. 4B) are alternatelyarranged with the other two contact electrodes that are disposed oncontacts coupled to a second set of planar conductors, such aseven-numbered planar conductive layers (e.g., contact electrodes 441 band 441 d coupled to contacts 431 b in FIG. 4A, and contact electrodes442 b and 442 d coupled to contacts 432 b in FIG. 4B). In FIG. 4A,contacts 431 a and 431 b are disposed on only one of the two side ofcapacitor 401 viewed in the direction perpendicular to the lateral sidesof the steps thereon (e.g., each of the left and right sides ofcapacitor 401 viewed in the direction of the y axis shown in FIG. 4A).In FIG. 4B, however, contacts 432 a and 432 b are disposed on both sidesof capacitor 402 viewed in the direction perpendicular to the lateralsides of the steps thereon (e.g., both sides of capacitor 402 viewed inthe direction of the y axis shown in FIG. 4B). The arrangements ofcontact electrodes shown in FIGS. 4A and 4B may provide, further to thecapacitance provided by their stacked bodies, additional capacitancebetween the contact electrodes.

The capacitors described in conjunction with the preceding figures maybe fabricated into a variety of semiconductor devices to be used as apassive circuit element therein. Especially, by virtue of theirstructural configurations hitherto described, capacitors in accordancewith the present disclosure may be fabricated concurrently with othersemiconductor elements, such as a three-dimensional memory cell arraystructure of a flash memory device. In this regard, FIG. 5 shows across-sectional view of an illustrative embodiment of a flash memorydevice including a capacitor in accordance with the present disclosure.Referring to FIG. 5, a flash memory device 500 may include a memory cellarray region 51 and a periphery region 52.

Memory cell array region 51 may include a three-dimensional memory cellarray structure 501. Three-dimensional memory cell array structure 501may include a substrate 560, a dielectric layer 561 located on substrate560, and a stacked body 570 located on dielectric layer 561 andalternately stacked with planar conductors (e.g. planar conductivelayers 571 a-571 d) and dielectrics (e.g. dielectric layers 572 a-572c). Stacked body 570 may include one or more pillar-shaped semiconductorstructures (e.g., a pillar-shaped semiconductor structure 56) that mayrespectively function as a string of three dimensional flash memorycells. Each pillar-shaped memory structure may include, for example, asilicon pillar (e.g., a silicon pillar 57) and an oxide-nitride-oxide(ONO) film (e.g., an ONO film 58) encircling the silicon pillar. Eachplanar conductive layer 571 a-571 d functions as a word line forcontrolling the portion of pillar-shaped memory structure 56 itencircles. For example, the portion of ONO film 57 surrounded by planarconductive layer 571 a may function as a transistor that turns on andoff depending on the voltage applied by planar conductive layer 571 afunctioning as a word line thereto. Each planar conductive layer 571a-571 c is respectively connected to contact electrodes 590 a-590 cthrough contacts 580 a-580 c formed in a dielectric layer 599 to besupplied with program and other types of voltages. The concreteconfigurations of a three-dimensional memory cell array structure arewell known in the pertinent art, and are not further described for thesake of simplicity.

Periphery region 52 may be formed with a variety of structures/circuitsfor operating three-dimensional memory cell array structure 501. Forexample, periphery region 52 may include one or more capacitors inaccordance with the present disclosure to supply necessary voltages tothree-dimensional memory cell array structure 501 and/or other parts offlash memory device 500. In this regard, FIG. 5 shows a portion 502 ofsuch a capacitor. The capacitor may include a substrate 510, adielectric layer 511 located on substrate 510, and a stacked body 520located on dielectric layer 511 and alternately stacked with planarconductors (e.g. planar conductive layers 521 a-521 d) and dielectrics(e.g. dielectric layers 522 a-522 c). Each planar conductive layer 521a-521 c is respectively connected to one of multiple contact electrodes(e.g., a contact electrode 540) through one of contacts 530 (e.g.,contacts 530 a and 530 b) formed in an dielectric layer 550 to besupplied with a charging voltage. As can be appreciated from FIG. 5, theconfiguration of the three-dimensional memory cell array structure andthe capacitor have similar structural configuration, thus, the capacitormay be fabricated in conjunction with and/or concurrently with thethree-dimensional memory cell array structure in the memory cell arrayregion. Further, the above similarity allows fabrication of thecapacitor, for example, by using the structure(s) that are naturallyformed in the peripheral region during the fabrication of thethree-dimensional memory cell array structure in the memory cell arrayregion. This will become clearer as we describe an example fabricationprocess of a capacitor in accordance with this disclosure with regard toFIGS. 7 and 8A-8G.

The capacitors described in conjunction with the preceding figures maybe used for a variety of devices formed in a peripheral region of asemiconductor device. By way of a non-limiting example, capacitors inaccordance with the present disclosures may be used as capacitiveelements in a charge pump for providing voltages, for example, tocontact electrodes 590 a-590 c of three-dimensional memory cell arraystructure 501 shown in FIG. 5. In this regard, FIG. 6 shows anillustrative embodiment of a charge pump including multiple capacitorsin accordance with the present disclosure. Referring to FIG. 6, a chargepump 600 may include a plurality of pump stages 610-630 respectivelycoupled to capacitors 611 and 612, 621 and 622, and 631 and 632.Capacitors 611, 621, and 631 may be provided with a clock pulse CLK_(a),while capacitors 611, 621, and 631 may be provided with a clock signalCLK_(b), which is of the same magnitude as clock signal CLK_(a) butshifted in phase by 180 degrees. The above capacitors may store energywhen clock pulse CLK_(a) or CLK_(b) is at Vcc [V], and discharge theenergy stored therein when clock pulse CLK_(a) or CLK_(b) is at 0[V].Each pump stage 610-630 is made of one or more transistors that, whenprovided with voltage signals discharged from the capacitors, turns onand conveys the voltage signals provided thereto as output. Thecapacitors in FIG. 6 may provide greater capacitance and store moreenergy than conventional capacitors (e.g., MOSFET capacitors), whilebeing smaller in size. This allows increasing the voltage output ofcharge pump 600 without adding an additional pump stage(s) thereto(i.e., without increasing the size and cost of charge pump 600).

A method for fabricating a capacitor is explained hereafter withreference to FIGS. 7 and 8A-8G. FIG. 7 shows an example flow diagram ofan illustrative embodiment of a method for fabricating a capacitor.Referring to FIG. 7, a substrate may be prepared (block 710). Thesubstrate, for example, may be prepared by using any of the materialsdescribed above with reference to FIGS. 1A-1C (e.g., materials describedabove with reference to FIG. 1A through FIG. 1C such as, for example,sapphire, glass, or semiconductor materials (e.g., silicon (Si),germanium (Ge), and gallium arsenide (GaAs). In one embodiment, thesubstrate may be a substrate for a flash memory device including amemory cell array region and a peripheral region. In block 720, N planarconductors (e.g. planar conductive layers) are alternately stacked withN−1 dielectrics (e.g. N−1 dielectric layers) on the substrate to form astacked body thereon. In the embodiment where the substrate is asubstrate for a flash memory device, the planar conductive layers andthe dielectric layers may be alternately stacked in both the memory cellarray region and the peripheral region. In this regard, FIG. 8A shows across-sectional view of an illustrative embodiment of portions 819 and869 of a stacked body respectively formed in a peripheral region 82 anda memory cell array region 81 located on substrates 860 and 810. In FIG.8A, the planar conductive layers and the dielectric layers arerespectively referenced with numerals 821 a-821 d and 822 a-822 c (forstacked body portion 820) and 871 a-871 d and 872 a-872 c (for stackedbody portion 870). Further, in some embodiments, as shown in FIG. 8A,dielectric layers 861 and 811 may be located on substrates 860 and 810,respectively.

In block 730, one or more portions of the stacked body are removed touncover one or more portions of each of the planar conductive layersthat were previously covered by their overlying planar conductive and/ordielectric layers. By way of a non-limiting example, the stacked bodymay be etched with a mask having a width that decreases with eachiteration (i.e., a mask slimmed with each iteration) to form a stairstep at one or more sides of the stacked body. In the embodiment relatedto a flash memory device, the portions of the stacked body in both thememory cell array region and the peripheral region may be etched, forexample, concurrently, so as to provide two separate stacked bodies inthe respective regions. FIG. 8B shows a cross-sectional view of anillustrative embodiment of portions 820 and 870 of the stacked bodyrespectively iteratively etched with a mask (not shown) having a widththat decreases with each iteration (i.e., W1, W2, and W3) to be formedinto two separate stacked bodies 820 and 860 each having a stair step.There are various techniques known in the art, including theaforementioned mask slimming technique, for fabricating theaforementioned stair-stepped structure in a stacked body, all of whichmay be applied to a stacked body of the present disclosure. Thetechnical details thereon are not further described for the sake ofsimplicity.

In the embodiment related to a flash memory device, before or afterblock 730, the stacked body in the memory cell array region may beprocessed to form therein one or more pillar-shaped semiconductorstructures that may respectively function as a string of threedimensional flash memory cells. Each pillar-shaped memory structure mayinclude, for example, a silicon pillar (e.g., epitaxial silicon orpolysilicon) and an oxide-nitride-oxide (ONO) film encircling thesilicon pillar. In this regard, FIG. 8C shows a cross-sectional view ofan illustrative embodiment of a pillar-shaped semiconductor structure 86including a silicon pillar 87 and an ONO film 88. The techniques forfabricating the aforementioned pillar-shaped semiconductor structure arewell known in the pertinent art, and are not further described for thesake of simplicity.

In block 740, one or more contacts are formed on the stacked body. Theone or more contacts may be substantially perpendicular to the uppersurfaces of the stacked body. One set of contacts may be coupled to theuncovered portions of a first set of planar conductors (e.g.odd-numbered planar conductive layers), whereas another set of contactsmay be coupled to the uncovered portions of a second set of planarconductors (e.g. even-numbered planar conductive layers).

In one embodiment, the contacts may be formed by forming an interlayerdielectric layer over the stacked body, and removing one or portions ofthe interlayer dielectric layer above at least some of the one or moresecond portions of planar conductive layers to define one or moreopenings (e.g., holes) therethrough, and depositing conductive materialsinto the one or more openings to form the contacts therein. In theembodiment related to a flash memory device, one or more contacts mayalso be formed in the memory cell region. For example, the one or morecontacts in the memory cell region may be formed concurrently with thecontacts in the periphery region, by also depositing an interlayerdielectric layer in the memory cell region, forming one or more openingsin the interlayer dielectric layer, and depositing a conductive materialinto the openings to form one or more contacts therein. In this regard,FIG. 8D shows a cross-sectional view of an illustrative embodiment ofinterlayer dielectric layers 850 and 899 respectively formed inperiphery and memory cell array regions 82 and 81. FIG. 8E shows across-sectional view of an illustrative embodiment of openings 829 a and829 b formed in periphery region 82 located on substrate 810, andopenings 879 a-879 c formed in memory cell array region 81 located onsubstrate 860. Further, FIG. 8F shows a cross-sectional view of anillustrative embodiment of contacts 830 a and 830 b and contacts 880a-880 c respectively formed in periphery and memory cell array regions82 and 81.

In block 750, two or more contact electrodes are formed on the contacts.For example, a first contact electrode may be formed on a first set ofcontacts coupled to the odd-numbered planar conductive layers and asecond contact electrode may be coupled to a second set of contactscoupled to even-numbered planar conductive layers. In one embodiment,the first and second electrodes may be formed above the first and secondsides of the stacked body at which stair steps are respectively formed.In another embodiment, the first and second contact electrodes may beformed above a stair step adjacent to first and second lateral sides ofthe stair step, respectively. Further, in yet another embodiment, inaddition to the first and second electrodes, additional contactelectrodes may be formed. For example, third and fourth contactelectrodes may be respectively formed to be disposed on and coupled toat least some of the first set of contacts and at least some of thesecond set of contacts. The third contact electrode may be interposedbetween and adjacent to the second and fourth contact electrodes toprovide capacitance between at least the second and third contactelectrodes or the third and fourth contact electrodes.

In the embodiment related to a flash memory device, one or more contactelectrodes may also be formed in the memory cell region. In this regard,FIG. 8G shows a cross-sectional view of an illustrative embodiment of acontact electrode 840 formed in peripheral region 82 for a capacitor inaccordance with present disclosure and contact electrodes 890 a-890 cfor the three-dimensional memory cell array formed in memory cell arrayregion 81.

As can be appreciated from FIGS. 8A-8G, a capacitor may be formed byusing a portion of a stacked body of alternating planar conductivelayers and dielectric layers that is naturally formed in the peripheralregion as well as the memory cell array region during the process offabricating a flash memory device. Further, by virtue of its structuralconfiguration, a capacitor in accordance with the present disclosure maybe formed in conjunction with and/or concurrently with the memory cellarray structure (e.g., a three-dimensional memory cell array structure)in the memory cell array region.

FIG. 9 shows a schematic diagram of an illustrative embodiment of asystem including a non-volatile memory device (e.g., a flash memorydevice 500 of FIG. 5). A system 900 may be used in devices such as, forexample, a personal digital assistant (PDA), a laptop or portablecomputer with wireless capability, a web tablet, a wireless telephone, apager, an instant messaging device, a digital music player, a digitalcamera, or other devices that may be adapted to transmit and/or receiveinformation either wirelessly or over a wire connection. The system 900may be used in any of the following systems: a wireless local areanetwork (WLAN) system, a wireless personal area network (WPAN) system,or a cellular network.

The system 900 may include a controller 910, an input/output (I/O)device 920 (e.g., a keypad, display), the flash memory device 500 ofFIG. 5, a wireless interface 940, and a static random access memory(SRAM) 960 and coupled to each other via a bus 950. A battery 980 maysupply power to the system 900 in one embodiment. The memory device mayinclude a NAND memory, a flash memory, a NOR memory, or the like.

The controller 910 may include, for example, one or moremicroprocessors, digital signal processors, micro-controllers, or thelike. The flash memory device 500 may be used to store messagestransmitted to or by the system 900. The flash memory device 500 mayalso optionally be used to store instructions that are executed bycontroller 920 during the operation of the system 900, and may be usedto store user data either generated, collected or received by the system900 (such as image data). The instructions may be stored as digitalinformation and the user data, as disclosed herein, may be stored in onesection of the memory as digital data and in another section as analogmemory. As another example, a given section at one time may be labeledas such and store digital information, and then later may be relabeledand reconfigured to store analog information.

The I/O device 920 may be used to generate a message. The system 900 mayuse the wireless interface 940 to transmit and receive messages to andfrom a wireless communication network with a radio frequency (RF)signal. Examples of the wireless interface 940 may include an antenna,or a wireless transceiver, such as a dipole antenna, although the scopeof the present disclosure is not limited in this respect. Also, the I/Odevice 920 may deliver a voltage reflecting what is stored as either adigital output (if digital information was stored), or as analoginformation (if analog information was stored). While an example in awireless application is provided above, embodiments of the presentinvention may also be used in non-wireless applications as well.

It should be appreciated that the structural and functionalconfigurations of a capacitor, a semiconductor device, and/or a systemand their elements described in conjunction with FIGS. 1A-9 areindicative of a few ways in which a capacitor, a semiconductor device,and/or a system may be implemented. It should be appreciated that acapacitor in accordance with this disclosure may be applied to any typeof devices and systems, including types of memories other than flashmemory.

One skilled in the art will appreciate that, for this and otherprocesses and methods disclosed herein, the functions performed in theprocesses and methods may be implemented in differing order.Furthermore, the outlined steps and operations are only provided asexamples, and some of the steps and operations may be optional, combinedinto fewer steps and operations, or expanded into additional steps andoperations without detracting from the essence of the disclosedembodiments.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isto be understood that this disclosure is not limited to particularmethods, reagents, compounds compositions or biological systems, whichcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular embodimentsonly, and is not intended to be limiting.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations). Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third, and upperthird, etc. As will also be understood by one skilled in the art alllanguage such as “up to,” “at least,” and the like include the numberrecited and refer to ranges which can be subsequently broken down intosubranges as discussed above. Finally, as will be understood by oneskilled in the art, a range includes each individual member. Thus, forexample, a group having 1-3 cells refers to groups having 1, 2, or 3cells. Similarly, a group having 1-5 cells refers to groups having 1, 2,3, 4, or 5 cells, and so forth.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A method of fabricating a capacitor, the methodcomprising: alternately forming N planar conductors with N−1 dielectricson a substrate thereby forming a stacked body, N being a natural numbergreater than 2; removing portions of the stacked body to progressivelyuncover respective portions on at least N−1 of each of opposite ends ofthe N planar conductive layers, the respective portions on each of theN−1 planar conductive layers formed such that overlying remaining onesof the N planar conductive layers or the N−1 dielectric material layersdo not cover the respective portions of a lower one of the N planarconductive layers, at least some of the N planar conductive layers toelectrically couple contacts formed starting at respective ones of the Nplanar conductive layers in a direction substantially normal to therespective ones of the N planar conductive layers at only one or bothends, thereby avoiding locating contacts at a point intermediary betweenthe ends of respective ones of the N planar conductive layers; andforming a first contact, a second contact, and a third contact eachelectrically coupled to a first planar conductive layer, a second planarconductive layer, and a third planar conductive layer of the N planarconductors, the first contact being disposed on a first lateral side ofa first end upper surface portion of the first planar conductive layer,the second contact being disposed on a second lateral side of the firstend upper surface portion of the second planar conductive layer, and thethird contact being disposed on a first lateral side of the first endupper surface portion of the third planar conductive layer, the firstcontact and the third contact being formed to be directly coupled to afirst contact electrode, and the second contact being formed to bedirectly coupled to a second contact electrode coplanar with the firstcontact electrode.
 2. The method of claim 1, wherein removing portionsof the stacked body comprises iteratively etching the stacked body withone or more masks having a width that decreases with each iteration toform a stair step at each of the opposite ends of the stacked body. 3.The method of claim 1, wherein alternate ones of the planar conductorsconstitute a first set, and remaining ones of the planar conductorsconstitute a second set.
 4. The method of claim 1, wherein forming thefirst contact and the second contact further comprises: forming aninterlayer dielectric layer over the stacked body; forming openings inthe interlayer dielectric layer; and forming a conductive material intoat least a portion of the openings to form the first contact and thesecond contact therein.
 5. The method of claim 3, further comprisingforming a first contact electrode and a second contact electroderespectively above the first contact and the second contact, the firstcontact electrode and the second contact electrode extendingsubstantially parallel to each other and in a direction substantiallyparallel to a direction along the only one or both ends of the N planarconductive layers.
 6. The method of claim 5, wherein removing portionsof the stacked body comprises removing portions of the stacked body toform a stair step at a first side of the stacked body and a stair stepat a second side of the stacked body, and wherein forming the firstcontact electrode and the second contact electrode comprises forming thefirst contact electrode and the second contact electrode above the firstside and the second side of the stacked body, respectively.
 7. Themethod of claim 5, wherein forming the first contact electrode and thesecond contact electrode comprises forming the first contact electrodeand the second contact electrode above the stair step adjacent to thefirst lateral side and the second lateral side of the stair step,respectively.
 8. The method of claim 5, wherein forming the firstcontact and the second contact comprises forming a plurality of firstcontacts and a plurality of second contacts, and wherein forming thefirst contact electrode and the second contact electrode furthercomprises forming a third contact electrode and a fourth contactelectrode respectively disposed on and coupled to at least some of thefirst contacts and at least some of the second contacts, respectively.9. The method of claim 1, wherein alternately stacking N planarconductors comprises alternately stacking N planar conductors with N−1dielectrics in a memory cell array region and a peripheral regionadjacent to the memory cell region to form the stacked body, and whereinremoving a portion of the stacked body comprises removing portions ofthe stacked body in the memory cell array region to form a threedimensional memory cell array structure.
 10. The method of claim 9,further comprising forming one or more pillar-shaped openings throughthe stacked N planar conductors and through at least some of the N−1dielectrics in the memory cell region.
 11. The method of claim 10,further comprising: forming an oxide-nitride-oxide (ONO) film in the oneor more pillar-shaped openings; and forming a silicon pillar within anopening formed within and encircled by the ONO film, the silicon pillarbeing separated from sidewalls of the one or more pillar-shaped openingsby the ONO film.
 12. A method, comprising: forming a stacked body on asubstrate, forming the stacked body including forming N planarconductive layers disposed one above the other, N being an integergreater than 2; and forming N−1 planar dielectric layers interposedbetween adjacent ones of the N planar conductive layers; removingportions of the stacked body including removing portions of at least N−1of the N planar conductive layers that are distal from the substrate touncover at least respective portions on at least each of opposite endsof remaining ones of the N planar semiconductor layers, the respectiveportions not covered by remaining ones of the N planar conductive layersdisposed above a lower level one of the N planar conductive layers, eachof the respective portions extending in a direction that issubstantially parallel to a plane of the N planar conductive layers; andremoving portions of the N−1 dielectric material layers, each of the N−1dielectric material layers being smaller than an underlying one of the Nplanar conductive layers such that at least a portion of the respectiveportions is not covered by the overlying one of the N−1 dielectriclayers; and forming a first contact, a second contact, and a thirdcontact each electrically coupled to the respective portions of the Nplanar conductive layers, the first contact, the second contact, and thethird contact being formed starting at respective ones of the N planarconductive layers in a direction substantially normal to the respectiveones of the N planar conductive layers and only at one or both ends ofrespective ones of the N planar conductive layers thereby avoidinglocating contacts at a point intermediary between ends of the respectiveN planar conducting layers, the first contact being disposed on a firstlateral side of a first end upper surface portion of a first of the Nplanar conductive layers, the second contact being disposed on a secondlateral side of the first end upper surface portion of a second of the Nplanar conductive layers, and the third contact being disposed on afirst lateral side of the first end upper surface portion of a third ofthe N planar conductive layer, the first contact and the third contactbeing formed to be directly coupled to a first contact electrode, andthe second contact being formed to be directly coupled to a secondcontact electrode coplanar with the first contact electrode.
 13. Themethod of claim 12, further comprising substantially concurrentlyforming the one or more stacked bodies in each of a memory cell regionand an adjacent peripheral region.
 14. The method of claim 13, furthercomprising forming a semiconductor structure through the stacked Nplanar conductive layers and through the N−1 planar dielectric layers inthe memory cell region.
 15. The method of claim 12, further comprisingforming a dielectric material between the substrate and the stackedbody.
 16. The method of claim 12, wherein the N−1 dielectric materiallayers, considered with the N planar conductive layers, form a dualstair-step structure.
 17. A method, comprising: forming N planarconductive layers disposed one above the other; forming N−1 dielectricmaterial layers, respective ones of the N−1 dielectric materials beinginterposed between respective adjacent pairs of the N planar conductivelayers; removing a respective portion on at least each of opposite endsof the N Planar conductive layers such that the respective portion isnot covering opposite ends of remaining ones of the N planar conductivelayers that are disposed below a higher level one of the N planarconductive layers; and removing a respective portion of each of the N−1dielectric material layers such that successive ones of the N−1dielectric material layers is smaller than an underlying one of the Nplanar conductive layers, at least some of the N planar conductivelayers to electrically couple contacts formed starting at respectiveones of the N planar conductive layers in a direction substantiallynormal to the respective ones of the N planar conductive layers at onlyone or both ends, thereby avoiding locating contacts at a pointintermediary between the ends of respective ones of the N planarconductive layers; and forming a first contact, a second contact, and athird contact each electrically coupled to a first planar conductivelayer, a second planar conductive layer, and a third planar conductivelayer of the N planar conductors, the first contact being disposed on afirst lateral side of a first end upper surface portion of the firstplanar conductive layer, the second contact being disposed on a secondlateral side of the first end upper surface portion of the second planarconductive layer, and the third contact being disposed on a firstlateral side of the first end upper surface portion of the third planarconductive layer, the first contact and the third contact being formedto be directly coupled to a first contact electrode, and the secondcontact being formed to be directly coupled to a second contactelectrode coplanar with the first contact electrode.
 18. The method ofclaim 17, further comprising forming a dual stair-step structure fromsuccessive ones of the N planar conductive layers and the N−1 dielectricmaterial layers.
 19. The method of claim 17, further comprising formingmore than three planar conductive layers.
 20. The method of claim 17,further comprising forming at least N contacts each electrically coupledonly at one or both ends of the N planar conductive layers.